If you delete a tag the effect will be that the according element is not part of the logical document structure anymore. Assistive technologies will ignore this element.
But: your PDF is not an accessible PDF that is compliant with DIN-/ISO-standard PDF/UA (14289-1:2012). This standard requires that all elements in a PDF has to be marked - either with an appropriate structure element (tag) or as an artifact.
There are tools available that are able to artifact all non-tagged elements - axesPDF QuickFix is one of that tools.